Vacuum circuit interrupter with condensing shield serving as one of the main contacts



Nov. 1, 1966 R. E. FRINK 3,283,100

A VACUUM CIRCUIT INTERRUPTER WITH CONDENSING SHIELD SERVING AS ONE OF THE MAIN CONTACTS Filed Nov. 16, 1964 5 Sheets-Sheet 1 INVENTOR Russell E. Frink ATTORNEY VACUUM CIRCUIT INTERRUPTER WITH CONDENSING SHIELD SERVING AS ONE OF THE MAIN CONTACTS 5 Sheets-Sheet 2 Filed Nov. 16, 1964 FIG. 2.

Nov. 1, 1966 R. E. FRINK VACUUM CIRCUIT INTERRUPTER WITH CONDENSING SHIELD SERVING AS ONE OF THE MAIN CONTACTS 5 Sheets-Sheet 5 Filed Nov. 16, 1964 United States Patent "ice Filed Nov. 16, 1964, Ser. No. 411,259 11 Claims. (Cl. 200-144) This invention relates generally to vacuum-type circuit interrupters having condensing-shield structures and, more particularly, to a vacuum-type circuit interrupter in which the condensing-shield structure serves as a component part of a main-contact structure, which electrically shunts the separable arcing contacts.

A general object of the present invention is to provide an improved vacuum-type circuit interrupter capable of carrying continuously a high-value load current.

A more specific object of the present invention is the provision of an improved vacuum-type circuit interrupter having a condensing shield which serves as a support for main contact fingers.

Still another object of the present invention is the provision of an improved vacuum-type circuit interrupter in which the condensing shield is at a floating potential, and in which said condensing shield provides a component part of a shunting main contact structure.

Still a further object of the present invention is the provision of high-capacity vacuum-type circuit interrupter in which a pair of main contacts is arranged to open before the arcing contacts open during the opening operation, and to close after the arcing contacts close during the closing operation, and in which the condensing-shield structure serves as a supporting means for the main contact structure.

Another object of the present invention is to provide an improved vacuum-type circuit interrupter in which the condensing-shield structure carries practically all of the load current in the closed-circuit position of the device.

An ancillary object of the present invention is the provision of an improved vacuum-type circuit interrupter having a condensing-shield structure, in which the condensing-shield structure provides a support for main contact fingers, and, additionally, provides a large-area radiating surface, which can readily radiate generated heat through the surrounding glass envelope.

In carrying out my invention in one form, I provide a condensing tubular shield with a plurality of circumferentially-disposed flexible main contact fingers, which cooperate with a moving main contact, which is arranged to open prior to the opening movement of the movable arcing contact. In another form of my invention, I utilize a condensing-shield structure having two sets of resilient main contact fingers at the opposite ends thereof, and employ two oppositely-movable main contacts, which respectively engage with the main contact fingers supported by the condensing-shield structure. In such a device, the two oppositely-disposed main movable contact structures separate from their cooperable main contact fingers prior to the separation of the two arcing electrodes, a lost-motion connection being provided, associated with each movable contact structure.

In still a third form of my invention, I provide a resilientlymounted movable condensing-shield structure associated with a vacuum-type circuit interrupter, in which the condensing-shield structure has two sets of main contact fingers disposed at the opposite ends thereof; and the entire condensing-shield structure is adapted to move with the main movable contact during the closing operation, until it engages the stationary serially-arranged main 3,283,100 Patented Nov. 1, 1966 contact structure. Such an arrangement has the advantage thatthe condensing-shield structure is at a floating potential, so that voltage stress is minimized in the opencircuit position of the device.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings, in which:

, FIGURE 1 is a vertical cross-sectional view taken through a vacuum-type circuit interrupter employing the principles of the present invention, the contact structure being illustrated in the closed-circuit position;

FIG. 2 is a fragmentary enlarged sectional view taken through the actuating mechanism substantially along the line II--II of FIG. 1, again the contact structure being illustrated in the closed-circuit position;

FIG. 3 illustrates a modified form of the invention in which two movable main contact structures are utilized, the view being taken generally sectionally through the device, the contact structure being illustrated in the closedcircuit position; and,

FIG. 4 is a vertical sectional view taken through another form of the present invention, the contact structure being illustrated in the closed-circuit position.

Referring now to the circuit interrupter 9 of FIG. 1, there is shown a highly-evacuated envelope 10 comprising a casing 11 of suitable insulating material, for example glass, and a pair of end plates 12, 13 closing off the ends of the casing. Suitable seals 12a, 13a are provided between the end plates 12, 13 and the glass casing 11 to provide vacuum-tight joints at these points.

Located within the envelope 10 is a pair of separable arcing contacts 15, 16, which are electrically shunted by a main contact structure, generally designated by the reference numeral 17, and comprising a plurality of circumferentially-disposed flexible contact fingers 18 and a main contact member 19.

As shown in FIG. 1, the set of resilient main contact fingers 18 is supported by a metallic cylindrical oondensing shield 20, the latter being secured, as by brazing, to the upper end plate 12. For certain applications, it may be desirable to form the main stationary resilient contact fingers 18 by slotting a metallic cylinder C, and bending the resulting fingers inwardly, as shown in FIG. 1. The slotted cylinder C may then serve as a contact ring, and be suitably affixed to the inner surface of the condensing shield 20, as shown.

As well known by those skilled in the art, in a vacuum circuit interrupter, the metallic vapors that are produced by arcing tend to condense on the insulating surfaces of the interrupter and, tend to form metallic coatings which impair the insulating properties of such surfaces. For protecting these insulating surfaces against such metal deposition, a condensing-shielding structure is utilized. Generally, such shielding structure comprises a generally tubular metallic shield surrounding the arcing gap between the usual arcing electrodes of the interrupter, and electrical-1y isolated from one or both end plates of the device. The electrically-isolated shield is physically located between the arcing gap and the internal surface of the usual insulating casing for the interrupter, and acts to intercept and condense those metallic vapors traveling toward the insulating surface from the arcing gap.

As shown in FIG. 1, the lower end plate 13 has a downwardly-extending cylindrical guide-flange portion 13!), which guides the reciprocal vertical opening and closing movement of the main contact member 19, which engages the stationary resilient main contac': fingers 18 in the closed-circuit position of the device, as shown in FIG. 1.

The main contact member 19 has a reduced portion 19a forming a shoulder 1%, which accommodates a linetermin-al connector 22 having a flexible strap-like main line connector 23 fixedly secured thereto, as by a rivet 25. A locking nut 28 is threaded upon a threaded portion 190 of the reduced stem portion 19a, and securely fixes the line connector 22 to the movable main contact member 19.

As shown in FIG. 2, the movable line connector 22 is of generally a U-sha-pe having outwardly-projecting trunnion studs 30', which are pivotally connected to insulating operating links 31. Thu-s, each vacuum-type circuit-interrupting unit 9 has a pair of cooper-able actuating links 31, preferably composed of insulating material, which effect reciprocal opening and closing movement of the U-shaped line connector 22, and hence the main movable contact member 19.

To prevent leakage of gas between the downwardlyextending flange portion 13b of the end plate 13 and the reciprocally-movable main contact member 19, there is provided a flexible metallic bellows 35. The upper end of the bellows 35, as viewed in FIG. 1, is secured by means of suitable sealed joints to the end plate 13. The lower end of the bellows 35 is secured by suitable means to the lower external side surface of the main movable contact 19, as shown.

A bore 19d is provided longitudinally through the main movable contact member 19, and accommodates reciprocal opening and closing motion of the arcing contact 16. A second flexible metallic bellows 37 is secured between an outwardly-extending flange portion 16a and an upper planar portion 19a of the main movable con-tact 19 to prevent leakage of gas along the bore 19d into the interior 40 of the evacuated envelope A compression spring 16b is interposed between flange 16w and the bottom of a spring bore 19f of the main movable contact member 19 to bias the movable arcing contact 16. upwardly against the stationary arcing contact 15.

A pair of retaining nuts 42, 44 fixedly secure a flexible conducting strap 46 to a lower threaded portion 16c of the movable arcing electrode 16. The other end of the flexible strap-like lead 46 is connected, by an attachment bolt 48, to the movable line connector 22, as shown in MG. 1. Thus, the two movable arcing and main contacts 16, 19 are electrically connected together at all times.

As illustrated in FIG. 1, the upper end plate 12 has fixedly secured thereto, :as by bolts 50, 52, a line bus bar 54, to which the line connection L may be connected by any suitable means.

As pointed out hereinbefore, in a vacuum-type circuit interrupter, the metallic vapors that are produced during arcing tend to condense on the insulating surtaces of the interrupter casing, and hence to form metallic coatings which impair the insulating properties of such surfaces. For protecting the surfaces against such metal deposition, a condensing shield 20 has been found particularly effective. Generally, such a condensing shield 20 comprises a tubular metallic member surrounding the arcing gap between the usual electrodes of the interrupter, and electrica ly isolated from both electrodes and from ground. This electrically-isolated shield is physically located between the arcing gap and the internal surface of the usual insulating casing 11 for the interrupter, and acts to intercept and condense those metallic vapors traveling toward the insulating surface from the arcing gap.

As provided herein, the condensing shield 20 constitutes a component part of the main contact structure 17 which shunts the arcing contact structure, and enables the circuit interrupter to carry higher load currents without heating.

The condensing-shield structure 20, as shown, constitutes-an integral part of the main current path in the closed-circuit position of the interrupter, as illustrated in FIG. 1.

During the opening operation, the pair of insulating links 31 are moved downwardly by any suitable actuating mechanism. Such action causes the U-shaped line connector 22 to also move down, which, in turn, causes downward opening movement of the main movable contact 19,

moves downwardly and, following abutting engagement- -between the lower extremity 19g and the retainer bolt 42, the movable arcing contact 16 is forced to move downwardly with the main movable contact 19, drawing an are between the arcing contacts 15, 16, which is extinguished in the usual manner. It will be noted, therefore, that the main movable contacts 18, 19 separate before separation of the arcing contacts 15, 16, so that no arc crrosion occurs at the contact structure 18, 19'.

During the closing operation, the insulating links 31 move upwardly to first cause re-engagement between the separable arcing contacts 15, 16, and further upward movement, ascaused by the insulating links 31, ultimately effects re-engagement between the main movable contact 19 and the flexible contact fingers 18 to thereby shunt the arcing contacts 15, 16. As a result, in the closed-circuit position of the interrupter, as illustrated in FIG. 1, the main contact structure 18, 19 electrically parallels the current path between the larcing contacts 15, 16, and due to the lower resistance carries practically all of the current.

From the foregoing description it will be apparent that the usual metallic condensing shield 20 has an important additional function, namely of providing a component part of the main contact structure 18, 19 shunting the arcing electrodes, and enabling the current to be increased without excessive heating. Due to the fact that the condensing shield 20 sees through the glass envelope 11, heat may be readily radiated by the condensing shield 20 through the glass envelope 11 to be quickly dissipated.

FIG. 3 shows a modified-type of interrupting arrangement 60, wherein the movable arcing and main contact structure 16, 19 of FIG. 1 is duplicated so that in eflect a mirror image structure about the center line CL is provided on the top and bottom of the interrupter 60. As a result, two main contact breaks are provided before the establishment of an arcing gap, and support of the condensing shield 20a is provided between the envelope sections 11a, 11b by a support ring 57. The shield 20a being electrically isolated in the open-circuit position reduces the voltage stress between the shield 20a and the movable -main contacts 19, 19A.

During the opening operation of the modified-type of circuit interrupter 60, the main movable contact structure 19 moves downwardly, whereas the cooperating main movable contact structure 19A moves upwardly. Thus, two simultaneous main breaks are obtained, and subsequently the two movable arcing contacts 16, 16A are separated to bring about circuit interruption.

During the closing operation, the oppositely-disposed main and movable arcing contacts 16, 19 are moved toward each other and make closing engagement, as illustrated in FIG. 3 of the drawings.

FIG. 4 illustrates a modified-type of interrupting arrangement 61 in which the condensing shield 20b is resiliently mounted by a plurality of compression springs 62 encircling spring bolts 63, the latter being disposed circumferentially around a supporting ring 64, which is sealed between two casing sections 11a, 11b of the interrupter 61. During the closing operation, the movable condensing shield 20b is moved upwardly by the lower main movable contact structure 19, until contact engagement is made at the upper set of main contact fingers 66 with astationary main contact ring 67.

During the opening operation, downward opening movement of the lower main movable contact 19 causes the condensing shield 20b to move therewith until separation is made at the upper main contact fingers 66, 67. Subsequently, the second set of main contact fingers 18,

19 separate, and, finally, the arcing contacts 15, 16 separate in the same manner as illustrated in FIG. 1 of the drawings.

From the foregoing description, it will be apparent that I have provided an improved condensing-shield structure which not only provides its usual function, but, additionally, provides a main-current breaking function to increase the load-current-carrying capacity of the interrupter without excessive heating.

Although there have been illustrated and described specific structures, it is to be clearly understood that the same were merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art, without departing from the spirit and scope of the invention.

I claim as my invention:

1. A vacuum-type circuit interrupter including a tubular envelope of insulating material, a tubular metallic condensing shield disposed internally of said envelope in generally concentric relationship with respect to said envelope for protecting said envelope from being coated with metallic particles, a pair of separable arcing contacts disposed within said condensing shield, a pair of separable main contacts within said envelope in electrically parallel relationship with respect to said separable arcing contacts, means separating the main contacts during the opening operation before separation of the arcing contacts, the condensing shield being electrically connected to one of the separable arcing contacts in the closed-circuit position, and said tubular metallic condensing shield comprising a component part of one of said separable main contacts to assist in carrying the continuous current through the interrupter.

2. A vacuum-type circuit interrupter including a tubular envelope of insulating material, a tubular metallic condensing shield disposed internally of said envelope in generally concentric relationship with respect to said envelope for protecting said envelope from being coated with metallic particles, a pair of separable arcing contacts disposed within said condensing shield, a pair of separable main contacts Within said envelope in electrically parallel relationship with respect to said separable arcing contacts, means separating the main contacts during the opening operation before separation of the arcing contacts, said main contacts comprising a circumferential set of resilient stationary main contact fingers and a movable main contact, the condensing shield being electrically connected to one of the separable arcing contacts in the closed-circuit position, and the condensing shield supporting said circumferential set of resilient stationary main contact fingers to assist in carrying the continuous current through the interrupter.

3. In combination, a vacuum-type circuit interrupter including a pair of separable arcing contacts, an electrically parallel pair of main separable contacts to assist in carrying load current through the interrupter, an evacuated envelope within which all said contacts are disposed, a tubular metallic condensing shield disposed internally of said envelope in generally concentric relationship with respect to said envelope and surrounding said arcing con tacts for protecting said envelope from being coated with metallic particles, means mounting one main contact upon said tubular metallic condensing shield so that main current flows through the condensing shield, means electrically connecting said condensing shield with one of the arcing contacts in the closed-circuit position, and means opening the main contacts before the arcing contacts during the opening operation.

4. A vacuum-type circuit interrupter including a tubular envelope of insulating material, a tubular metallic condensing shield disposed internally of said envelope in generally concentric relationship with respect to said envelope for protecting said envelope from being coated with metallic particles, a pair of separable arcing contacts disposed within said shield, separable main contact means Within said envelope in electrically parallel relationship with respect to said separable arcing contact means and comprising two sets of separable main contacts, said condensing shield being movable and in series circuit with said main contact means, means electrically connecting said condensing shield with one of the arcing contacts in the closed-circuit position, and said condensing shield carrying two sets of movable main contacts.

5. The combination of claim 1, wherein a lost-motion connection is provided between the main and-arcing contacts.

6. A vacuum-type circuit interrupter including a tubular envelope of insulating material, a tubular metallic condensing shield disposed internally of said envelope in generally concentric relationship with respect to said envelope for protecting said envelope from being coated with metallic particles, separable arcing contact means disposed within said shield, separable main contact means within said envelope in electrically parallel relationship with respect to said separable arcing contact means and including two sets of separable main contacts, means separating the main contact means during the opening operation before sepa ration of the arcing contact means, said condensing shield being electrically connected with the arcing contact means in the closed-circuit position, and said tubular metallic condensing shield supporting one contact of the two separable sets of main contacts adjacent opposite ends thereof.

7. The combination according to claim 6, wherein the condensing shield is movable and provides sequentiallyacting main contact gaps.

8. A vacuum-type circuit interrupter including a tubular envelope of insulating material, a tubular metallic condensing shield disposed internally of said envelope in generally concentric relationship with respect to said envelope for protecting said envelope from being coated with metallic particles, separable arcing contact means disposed Within said shield and comprising two oppositely movable arcing contacts, main contacts adjacent opposite ends of the condensing shield, said condensing shield being electrically connected with the arcing contacts in the closed-circuit position, and a pair of oppositely-movable main contacts engageable with said main contacts supported by the condensing shield.

9. A vacuum-type circuit interrupter including a tubular envelope of insulating material, a tubular metallic condensing shield disposed internally of said envelope in generally concentric relationship with respect to said envelope for protecting said envelope from being coated with metallic particles, separable arcing contact means disposed within said shield, separable main contact means within said envelope in electrically parallel relationship with respect to said separable arcing contact means and including two sets of movable main contacts disposed adjacent opposite ends of the condensing shield, a stationary main contact supported by an end plate of the interrupter and making engagement with one movable main contact supported by the condensing shield, and another movable main contact disposed adjacent the other end of the envelope making engagement with the other movable main contact supported by the condensing shield.

10. A vacuum-type circuit interrupter including an evacuated envelope, a resiliently-mounted movable condensing shield disposed internally of said envelope in generally concentric relationship with respect to said envelope for protecting said envelope from being coated with metallic particles, movable main contacts carried adjacent opposite ends of the condensing shield, a pair of separable arcing contacts disposed within the shield, and first stationary and second movable main contacts respectively sequentially engageable with the two main movable contacts carried by the condensing shield.

11. A vacuum-type circuit interrupter including a generally cylindrically-shaped insulating envelope, an internally-disposed generally cylindrically-shaped conducting condensing shield in generally concentric relationship 7 S therewith, a pair of separable arcing contacts disposed in- References Cited by the Examiner .ternally of said condensing shield, main contact means for increasing the current-carrying capacity including at least UNITED STATES PATENTS portions of the walls of said condensing shield in electri- 2,863,026 12/1958 Jennings 200-144 cally parallel relationship With respect to the arcing con- 5 2,972,032 2/1961 Persson 200-444 tacts, means opening the main contact means prior to 3,174,019 3/1965 Jansson 200144 opening the arcing contacts during a circuit opening operation, and means closing the arcing contacts prior to clos- ROBERT K SCHAEFER Primary Examiner ing the main contacts during a closing operation of the interrupter. 10 ROBERT S. MACON, Examiner. 

1. A VACUUM-TYPE CIRCUIT INTERRUPTER INCLUDING A TUBULAR ENVELOPE OF INSULATING MATERIAL, A TUBULAR METALLIC CONDENSING SHIELD DISPOSED INTERNALLY OF SAID ENVELOPE IN GENERALLY CONCENTRIC RELATIONSHIP WITH RESPECT TO SAID ENVELOPE FOR PROTECTING SAID ENVELOPE FROM BEING COATED WITH METALLIC PARTICLES, A PAIR OF SEPARATE ACING CONTACTS DISPOSED WITHIN SAID CONDENSING SHIELD, A PAIR OF SEPARABLE MAIN CONTACTS WITHIN SAID ENVELOPE IN ELECTRICALLY PARALLEL RELATIONSHIP WITH RESPECT TO SAID SEPARABLE ARCING CONTACTS, MEANS SEPARATING THE MAIN CONTACTS DRING THE OPENING OPERATION BEFORE SEPARATION OF THE ARCING CONTACTS, THE CONDENSING SHIELD BEING ELECTRICALLY CONNECTED TO ONE OF THE SEPARABLE ARCING CONTACTS IN THE CLOSED-CIRCUIT POSITION, AND SAID TUBULAR METALLIC CONDENSING SHIELD COMPRISING A COMPONENT PART OF ONE OF SAID SEPARABLE MAIN CONTACTS TO ASSIST IN CARRYING THE CONTINUOUS CURRENT THROUGH THE INTERRUPTER. 